Travunijana robusta robusta (Schütt, 1959) comb. nov.

Figs 7 L–M, 13A, 15A–B

Plagigeyeria robusta Schütt, 1959: 186, fig. 1.

Plagigeyeria robusta – Schütt 1972: 115, 123, pl. 8 figs 23–24. — Willmann & Pieper 1978: 126. — Bole & Velkovrh 1986: 202. — Bodon, Manganelli & Giusti 1996: 33, fig. 13. — Bank 2013: Fauna Europaea v. 2.6 — Bank & Neubert 2017: 25.

Diagnosis

Robust oval-conical shell (2.1 mm) with thick walls, rounded apex, smooth or finely ribbed shell surface, elongate round-rhomboidal aperture with slightly protruded columellar fold, open umbilicus and not protruded aperture against basal shell profile. Lateral labral profile straight and columellar labrum possesses weak negative sinuation. Nepionic whorl with weakly cancellated surface and protoconch with distinct pitting. Pitting depth variable according to population: Vrelo “Vruljak 1” population with regular shallow pitting concentrating around the suture and very weak at central part of whorl; population from Vrelo “Tučevac” with overall regular deep pitting over the whole protoconch surface.

Distribution

Travunijana robusta is known from the spring group of Trebišnjica near Bileća and Vrelo Čepo near Čepelica (currently flooded by the Bilećko Jezero), and from Estavela “Obod” in Fatničko Polje (452 m a.s.l.), spring Dobričevo near Stepen in Gatacko Polje (936 m a.s.l.) (Schütt 1972), and from Vrelo “Goricki Studenac” (280 m a.s.l.), Vrelo “Vruljak 1” (282 m a.s.l.) and Vrelo “Tučevac” (275 m. a.s.l.) in Trebinje.

Remarks

Most of the robust Travunijana specimens found in the Trebišnjica River Basin are assigned to Travunijana robusta (Schütt, 1959) (Fig. 7 L–M) divided into two populations or maybe subspecies (Schütt 1972). The karst conduits north of the Trebišnjica valley (north of Popovo Polje) host the nominotypical subspecies. The karst conduits south of Popovo and Mokro Poljes are populated by T. robusta asculpta (Schütt, 1972) (Fig. 7N). Furthermore, each particular locality can have specific morphotypes (e.g., population in Vrelo “Tučevac” near Trebinje hosts its specific smooth-shelled morphotype with different aperture), which are for time being regarded as falling within one morphologically variable species.